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The PROFIBUS FamilyPROFIBUS Expo, Perth November 2011

Andy VerwerVerwer Training & Consultancy Ltd

Member of the PROFIBUS Association of Australia

Page 2The PROFIBUS Expo, Perth November 2011

Overview of Presentation

• Introduction to Fieldbus and industrial networking

• The PROFIBUS family:– DP

– PA

– PROFINET

• Automation system costs and life cycle.

• Profiles a key to vendor independence.

• PROFIBUS fault finding and diagnostics.

• Health checking and monitoring.

• Practical demonstrations.

The PROFIBUS Expo, Perth November 2011

• The first process control systems were distributed, using pneumatic, electrical and electronic controllers mounted in the field (i.e. factory or plant).

• The widespread introduction of digital control in the 1970s led to highly centralised systems with directly wired sensors and actuators.

History of Control and Automation Systems

Central control computer

Supervisory control

Direct digital control

Logical control

Field

Control room

Operator terminals

DAC/ADC DI/DO


History of Control and Automation Systems

• Programmable Logic Controllers (PLCs) were introduced for factory automation providing mainly logical control using mainly digital IO.

• PLCs are now also widely used in the process industries combined with networked SCADA.

SCADA operator and engineering

stations

PLC

Sensors Actuators

Field

Control room

IO

PLC

IO

Sensors Actuators


• 4 to 20 mA is an electronic current transmission standard that has been widely adopted since the earliest electronic devices.

• The “live-zero” means that failure of electrical supply is clearly distinguished from the minimum process value.

• In addition the 4 mA can be used to drive the transmitter electronics, giving cost-effective two-wire transmission

0% 100%Process value

Current/mA

20

4

4-20mA Electronic Transmission


• 4-20mA provides transmission of the main process variable.

• However, modern smart devices have many parameters or settings that are used for calibration, commissioning and fault-finding.

• In order to read and write these parameters, various digital communication schemes were introduced.

• A particularly successful solution was the HART protocol (Highway Addressable Remote Transducer Protocol), developed by Rosemount Inc. in the early 1980s.

• HART allowed device parameters to be communicated to and from the device via the 4-20mA cable.

HART Protocol


Hart Protocol

• Later, Hart became an open standard, administered by the HART Communication Foundation.

• The open standardisation of Hart was the key factor in its success, allowing one software tool to communicate with a range of sensors from different manufacturers.

• Hart is still in widespread use across the process industry.

• However, HART is not a fieldbus!


So, what is Fieldbus?

• Fieldbus is a digital communications for field-mounted instrumentation, actuation and control devices.

• Fieldbus provides a network - Many devices on one cable.

• The communication is two-way so that devices can receive information from controlling stations and also can send information to controlling stations.

• Fieldbus is firmly established as the connection technology of choice for control and monitoring.

• Fieldbus provides clear cost and operational benefits for even the smallest installation in any industry.


Fieldbus

• There are many advantages of fieldbus over traditionally wired control systems:

– Significant reduction in the amount of wiring, cable trays etc.

– More extensive data to and from devices, i.e. diagnostic information, device parameters etc.

– Centralised commissioning of devices.

– Device management and maintenance facilities.

– Greater flexibility in system layout and design.

– Ease of future expansion and modification.


PROFIBUS

• PROFIBUS (PROcess Field BUS) is a well-proven, widely accepted fieldbus standard, which is well supported with a wide range of devices, equipment, and tools.

• PROFIBUS has been around for 20 years.

– Developed in Germany by a consortium of 12 companies and 5 research institutes with money from the German Government.

• PROFIBUS has always been an “open” system

– I.e. openly published as a standard and supported by many manufacturers.


PROFIBUS Overview

• PROFIBUS is the world’s leading fieldbus system:– Approaching 40 million devices installed.

– Approximately 3,000 products from over 300 different suppliers.

• World wide support provided by PROFIBUS International:– Extensive web site <www.profibus.com> with up to date and downloadable information.

– Regional PROFIBUS Associations in 25 countries.

– Approximately 30 PROFIBUS International Competency Centres (PICCs) and Training Centres (PITCs).

– 10 Device test laboratories around the world.


• PROFIBUS FMS – Fieldbus Message Specification– The original PROFIBUS protocol. Provides flexible

communications for a wide range of applications. No longer supported but remains compatible with DP.

• PROFIBUS DP - Decentralised Periphery– Low cost, high speed, simple communications for general

automation applications.• PROFIBUS PA - Process Automation

– Developed specifically for the process industry to replace 4-20mA technology and HART communications. Two-wire connection carrying both power and data.

• PROFINET – Industrial Ethernet– Allows standard Ethernet to be used for real-time control– Open, transparent communication between PROFIBUS and

Ethernet. Offers integration between different fieldbus technologies.

The PROFIBUS family


The PROFIBUS family

• All PROFIBUS versions are totally compatible.– FMS, DP and PA can run on the same network.

– PROFINET is an industrial Ethernet technology, but remains totally compatible with PROFIBUS.

– In fact PROFIBUS is part of the PROFINET specification.


PROFIBUS and PROFINET cabling

• PROFIBUS DP and FMS use RS485 wiring.– Shielded, twisted pair cable (150Ω characteristic impedance).

• PROFIBUS PA uses different transmission and cable using Manchester Bus Powered (MBP) transmission.– Shielded, twisted pair cable (100Ω characteristic impedance).

• PROFINET uses Ethernet wiring, but to a higher standard than used in IT systems.– Shielded 4 core twisted pair cable (100Ωcharacteristic impedance).


Application areas

• Manufacturing AutomationCar manufacturingBottling systemsStorage systems

• Building AutomationTraffic automationHeating, air-conditioning

• Process AutomationWater and sewage treatment

Chemical and petrochemical plantsPaper and textile industries

• Power industry and power distributionPower plantsSwitchgear

• Functional safety systems

• High reliability systems

• Redundant systems.

Car manufactureWater

Treatment and sewage

Bottling Plants

Building Automation

Pipelines

Paper and Printing Industry

Food Industry

Precious metals recovery

Polymer production and

Storage

Brewing industry

Mining & Quarrying


The PROFIBUS family

PROFIBUS DP/FMS

PROFIBUS DP PROFIBUS PA

DPcells

Actuators Drives TransmittersControl valves

Remote I/O

Sensors

TCP/IP

Ethernet

Exi

HMI

Field level

Cell/control level

Factory/plant level

High speed, modest data

Demanding tasks, extensive data

PLC

PCDP/PA coupler


The PROFIBUS family

PROFInet


DPcells

Actuators Drives TransmittersControl valves

Remote I/O

Sensors

TCP/IP

Ethernet

Exi

HMI

Field level

Cell/control level

Factory/plant level

High speed, modest data

Demanding tasks, extensive data

PLC

PC

PROFInetOther fieldbus networks

AS-i


The Automation System Life Cycle

• The total cost of an automation system is not simply the procurement cost.

• Maintenance and fault finding are probably the largest component of the cost, particularly when we include plant down time due to failure.

Design

Installation

Commissioning

Maintenance

Modification

Expansion

Decommissioning

• The total cost is spread over the whole life cycle of the plant.


PROFIBUS and PROFINET Diagnostics

• PROFIBUS and PROFINET incorporate extensive standardised diagnostics that can help to identify failures and so reduce the maintenance costs.

• Every device has a standard block of diagnostics that can be used to diagnose and locate communications failures.

• In addition, extended diagnostics are defined that can be used to diagnose and locate peripheral faults (associated with the sensor or actuator).

• Modern PROFIBUS and PROFINET devices incorporate extensive diagnostics which can help to rapidly find failures and can even give pre-warning of impending malfunction and performance degradation.


What is PROFINET?

• PROFINET is an open Industrial Ethernet standard developed by the PROFIBUS Organisation.

• PROFINET– is completely standard Ethernet (IEEE802.3).

– operates at 100Mbit/s over twisted-pair copper or fibre-optic cables,

– makes use of TCP/IP and other IT standards for non-real-time communications (i.e. configuration and parameters).

– Provides a “real-time” channel for time-critical communications (i.e. process data)

• PROFINET is NOT PROFIBUS over Ethernet!

• However, PROFINET is well thought out to incorporate the requirements of modern systems based on the lessons learned from PROFIBUS.


Component

Based

Automation

Network Engineering

and Maintenance

Asset

Management

Deterministic real-time operation WEB

integration

Decentralized Peripherals

Safety and

Security

Integrationwith

Fieldbus

Wireless

PROFINET Scope and Application Areas

Motion Control

Process Control

Manufacture materials handing storage


PROFINET IO

• PROFINET IO provides decentralised peripherals using Ethernet connection and the PROFINET communication protocol.

• PROFINET IO uses Real-Time and Non Real-Time communications.

• PROFINET makes use of relevant TCP/IP protocols for setup, configuration and maintenance functions:– DHCP – Dynamic Host Configuration Protocol,

– DNS – Domain Name Service,

– SNMP – Simple Network Management Protocol,

– ARP – Address Resolution Protocol,

– HTTP – Web page access, and lots more!


The PROFINET OSI model

Network

PROFINET

Real-time channel

Standard Fast Ethernet

IEEE802.31 - Physical layer

2 - Data Link Layer

IP3 - Network Layer

TCP/UDP4 - Transport Layer

5 - Session Layer

6 - Presentation Layer

PROFINET Application Layer7 - Application Layer

Non time-critical communication

Real-time communication


PROFIBUSOSI Model

FMS DP PA

Physical (1)

Application (7)

OSImodel

Layers (3) to (6) not used in

fieldbus systems

Data Link (2)

RS485 / Fibre-Optic MBP(IEC61158-2)

Fieldbus Data Link (FDL)

DP cyclic functions (DPV0)also DPV1, DPV2 extensions

Fieldbus Message Specification


PROFINET IO

• The TCP/IP channel is used for non-time critical tasks.– Downloading of configuration, parameters,

– Diagnostics,

– Device management information, etc.

• The Real-Time channel is used for time-critical data:– Cyclic process data,

– Alarms and critical messages,

– Communication monitoring.

• The PROFINET application layer protocol is defined in the International Fieldbus standard IEC61158 (type 10).


PROFINET IO

• Many features that have been developed for PROFIBUS devices have been directly incorporated into PROFINET:

– Standardised module and channel-related diagnostics,

– Alarm and status information,

– Identification and Maintenance (I&M) functions,

– Time stamping,

– Highly deterministic process cycle timing (Isochronous operation),

– Device description file (GSD) for configuration of device, options and modules.


Component

Based

Automation

Network Engineering

and Maintenance

Asset

Management


integration

Decentralized Periphery

Safety and

Security

Integrationwith

Fieldbus

Wireless

PROFINET Scope

Motion Control

Process Control



Real-Time Operation

• What does “Real-Time” mean?

– A real-time control system responds in a deterministic manner within a time which is short compared to the plant response time.

– i.e. it depends on the application!

• Standard communications (IT)

– requires a response in the order of ~100ms.

• Factory automation

– requires a response time in the order of ~10ms.

• Motion control

– requires a response time in the order of ~1ms with a jitter <1µs.


Real-Time Operation

• PROFINET makes use of:

– TCP/IP for standard communications, achieving response times reliably less than 100ms.

– A Real-Time, RT, channel for I/O communications, achieving reliable cycle times < 10ms with <1ms jitter.

– Isochronous Real-Time, IRT, channel for highly deterministic performance (e.g. servos robotics NC), achieving reliable cycle times < 1ms with <1µs jitter.

• RT and IRT communications are totally compatible with TCP/IP since the information is transmitted as a standard Ethernet package.


Real-Time Operation

• PROFINET IRT complies with IEEE 1588 –“Precision clock synchronization protocol for networked measurement and control systems”.

• However this not always good enough!

• PROFINET extensions to IEEE 1588 provide better accuracy with:– Automatic determination and compensation of the network transmission time.

– Resulting in less than 1µs jitter at 100Mbit/s.


IsochronousReal-Time Performance

0 1ms Cycle time

n

100ms

TCP/IP traffic

100% jitter

10ms

15% jitter

RT traffic

IRT traffic

<1µs jitter


Component

Based

Automation

Network Engineering

and Maintenance

Asset

Management


integration

Decentralized Periphery

Safety and

Security

Integrationwith

Fieldbus

Wireless

PROFINET Scope

Motion Control

Process Control



Integration with Fieldbus

• PROFIBUS devices are widely used in many different application areas.

• This investment is protected with PROFINET for both manufacturers and end-users.

• PROFINET provides a transparent interface with PROFIBUS via a standardised gateway or “Proxy”.

• The Proxy is a PROFINET IO device on one side and a PROFIBUS master on the other.

• PROFIBUS Configuration is integrated into the PROFINET configurator and is downloaded via Ethernet.


Integration with Fieldbus

PROFIBUS DP

PROXY

PROFIBUS PA

INTERBUS-S

PROXY

PROFINET

Other fieldbusses?


• PROFINET builds on the success of PROFIBUS and ensures a future for both.

• PROFINET has been in development for about 10 years.

• Take up of Industrial Ethernet has been slower than initially predicted.

• PROFIBUS is still growing exponentially – currently approaching 40 million devices installed.

• Over 3 million PROFINET devices are currently installed – currently growing at about 40% per year!

Industrial Acceptance and Applications


Industrial Acceptance and Applications

• In 2004, AIDA, a consortium of the big four European automotive manufactures announced adoption of PROFINET as the industry standard.

• The main reasons for this decision were reported to be:– The integration of safety-related information,– The simple integration of existing PROFIBUS and Interbus

systems.


Some Myths about PROFINET

• PROFIBUS runs at up to 12Mbit/s, whereas PROFINET runs at 100Mbit/s. Therefore PROFINET is about 8 times faster than PROFIBUS.

NOT TRUE!

– PROFINET gives similar performance to PROFIBUS (perhaps up to twice as fast).

• PROFINET will replace PROFIBUS in the next five years.

NOT TRUE!

– PROFINET will replace some PROFIBUS DP devices, but PROFIBUS PA will continue.

– Both DP and PA will be supported for many years to come.


Some Myths about PROFINET

• PROFINET is not standard Ethernet

NOT TRUE!

– PROFINET always uses completely standard Ethernet. It just doesn’t always use TCP/IP protocols – only for non time critical communications.

• PROFINET systems can be maintained by our IT department.

TRUE, BUT NOT A GOOD IDEA!

– PROFINET is much more than just an IT network. Real time determinism, reliability, device diagnostics and security are all much more important than on IT systems

PROFIBUS and PROFINET Profiles


• What exactly is a “profile”?

– The PROFIBUS standard specifies what is required to ensure communication between masters and slaves, however it does not specify what the data represents, nor how it is organised!

– A profile is a clear description of a device in terms of its I/O data, operation and functions.

– A profile is manufacturer independent, so it provides a generic device with which to communicate.

PROFIBUS Profiles


• A profile provides an agreed way to map the process data onto the PROFIBUS data for a particular type of device.

• A common set of user parameters are normally defined in the profile for a particular type of device.

• A profile can define the operation of the device, i.e. operating modes, reaction to fault conditions, alarm handling, etc.

• Quality of measurement or status information can be defined in a profile.

• Maintenance and diagnostic features can also be defined in a profile.

PROFIBUS Profiles


• Profiles ensure device interchangeability.– i.e. swapping devices from different manufacturers without the need to alter software or I/O mapping.

• Profiles also significantly simplify commissioning and maintenance.– Because devices of a certain type all look the same. We know where to find parameters and settings etc.

– Also settings can easily be transferred from one device to another

• Profiles exist for a wide range of PROFIBUS devices:– Drives, encoders, numerical control, robot control– Human/machine interfaces (HMI)– Fail-safe and safety-critical systems– Sensors: temperature, pressure, flow etc.– Actuators and valves.

PROFIBUS Profiles


• The PA profile is applicable to a wide range of devices that are used in the process industry:– Transmitters (pressure, temperature, flow, level etc)

– Actuators, valves

– Binary I/O,

– Controllers,

– Analysers

• The PA profile defines a base set of device parameters for operation, commissioning, maintenance and diagnostics.

• A “PROFIBUS PA” device must conform to the PROFIBUS DP protocol and the PA profile.

The PA Profile


The PA Profile

• The PA profile defines how the process value is transmitted:– As a 32-bit floating point value, scaled in engineering units.

– Plus a status byte showing the quality of the value.• I.e. Good, Uncertain Bad,

• and the reason:

• Eg: sensor failure, last usable value, conversion not accurate, simulated value etc.


PROFIDRIVE

• PROFIDRIVE is the name given to the PROFIBUS Drive Profile.

• PROFIDRIVE provides a standard, manufacturer-independent interface to variable-speed drives, positioning systems and servos.

• The PROFIDRIVE profile provides solutions for:– Simple motor soft stop/start with speed control.

– Distributed closed-loop speed/position control.

– Highly deterministic synchronised multi-axis servo control.


Functional Safety

• Functional Safety is concerned with the protection of people, environment, and livelihood –i.e. accident avoidance!

• Not to be confused with explosion prevention.

• Examples of safety protection systems include:– Emergency stop systems;

– Interlocking and safeguarding;

– Safe start-up and shut-down systems;

– Personnel access and guarding;

– Machinery interlocking.


• New standards provide for electronic/ programmable safety systems that can use fieldbus technology.

• PROFISAFE is a profile that allows us to use the same basic PROFIBUS and PROFINET technology for safety-related functions.

The Changing World of Safety Systems

• Safety Automation up to now has been prohibited from using fieldbus technology by old standards and requirements.

• Traditional safety systems had to be “hard-wired”.


PROFISAFE

• PROFISAFE is a functional safety solution that is designed to:– Meet the requirements of modern safety standards:

• IEC61508 (General standard),• IEC62061 (Machinery sector specific),• IEC61511 (Process sector specific);

– Provide a totally open, vendor independent, safety solution;

– Make full use of standard PROFIBUS and PROFINET diagnostics and troubleshooting features;

– Use existing tools for configuration, maintenance and fault-finding.


PROFIsafe

• This PROFIsafe solution is developed as a PROFILE– That is a component which sits above the PROFIBUS/PROFINET communication layers.

Standard protocol

Standardapplication

Safetyapplication

PROFIBUS or PROFINET

PROFISAFEprofile

Standard protocol

PROFISAFEprofile

PROFIBUS /PROFINET

“Black-channel”

PROFISAFE layer

Standardapplication

Safetyapplication

PROFIBUS fault finding and diagnostics


PROFIBUS DP/FMS


Ethernet

HMI

PLCPC

PSU

The Most Common PROFIBUS Problems

Number 2 - Interference pickup:Particularly on drives and servos.Number 2 - Interference pickup:Particularly on drives and servos.

Number 1 - Wiring faults:Reflections, Wire breaks, Short circuits, etc.

Number 1 - Wiring faults:Reflections, Wire breaks, Short circuits, etc.

Number 3 -Configuration faults.

Number 3 -Configuration faults.

?

Addressing faults.Addressing faults.

Device removalDevice removal

Power supply failure.

Power supply failure.

Instrument or I/O failure

Instrument or I/O failure


Problems with high speed networks

• Problems on high speed networks are more difficult to diagnose and locate than on low speed systems.

• The fact that we have a connection does not mean that the network will operate without errors.

• We can sometimes see devices that show intermittent faults caused by wiring and in installation errors.

• Often the devices that are most effected are at the other end of the cable from the fault.

• The correct tools and training are essential for fault finding.


Problems with high speed networks

• Quite often users are blissfully unaware that their system has communication errors because PROFIBUS robustness and fault tolerance can hide these faults.

Green light – all must be ok!

• Only when the rate of data corruption reaches a critical threshold will the fault become visible.


Reflections and Termination

• When electrical signals travel down a cable, any electrical discontinuity like a change in resistance, capacitance or the end of the wire, can cause reflections to occur.

• Just like an echo, the reflected signal can cause multiple signals to appear on the line. Reflections are bad news in high-speed communications because signals are corrupted or distorted by the reflection.

• The largest reflection is normally from the end of the cable, where the signal sees an abrupt change of impedance – a brick wall!





• To minimise reflections at the ends of a cable the two ends must be terminated with a specially chosen resistance that matches the cable “characteristic impedance”.

• The resistance absorbs the energy of the signal and significantly reduces the reflection (theoretically to zero).

• PROFIBUS RS485 uses “active termination” which means that the resistor network must be supplied with 5V.



390Ω

220Ω

390Ω

+5V (VP)

PROFIBUS cable

Screen

(DGND)

(RxD/TxD-P)

(RxD/TxD-N)

Red – B-line

Green – A-line

Normally built into connector.Can be switched in or out.



390Ω

220Ω

390Ω

+5V

Practical Demonstration

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